One example of such systems is a hearing aid, in which a so-called telecoil picks up an externally generated electromagnetic field, the coil signal is amplified, and the amplified signal is driving a loudspeaker (commonly called a “receiver”). In this system, the alternating current flowing in the power supply, the amplifier as well as the receiver, will produce an electromagnetic field. This field may induce a voltage in the telecoil, and a closed loop is formed. The result may be discretion in worst cases a loud audible feedback “howl”, which is undesirable and interferes with the desired operation of the system.
Previously a number of attempts have been made in order to reduce the effect of this electromagnetic feedback. These count magnetic shielding and spacing of the transducers. These attempts have some effect on reducing the feedback but still a significant part of the problem remains unsolved. Besides this the previously known solutions are difficult to handle from a manufacturing point of view and very non-desirable from a cosmetic point of view as the devices tend to be larger. There is therefore a need for improvement in handling this type of feedback
One objective of the present invention is to provide a method for use in a device as defined above and intended for reducing feedback in a manner where the system gain may be significantly increased compared to what has been possible until today without causing the creation of an oscillating feedback signal.
A further objective of the present invention is to provide a device of the type mentioned above where the system gain may be significantly increased compared to what has been possible until today without causing the creation of an oscillating feedback signal between the two transducers.